...derably the --preserve-merge option by adding a new option. "git rebase" learned "--rebase-merges" to transplant the whole topology of commit graph elsewhere. (Note: Git 2.22, Q2 2019, actually deprecates --preserve-merge, and Git 2.25, Q1 2020, stops advertising it in the "git rebase --help" outp...

... is closed gracefully are beyond the scope of this answer, if you want to learn more about, I recommend you have a look at this page. And even if you disabled lingering with SO_LINGER, if your process dies without explicitly closing the socket, BSD (and possibly other systems) will linger nonetheles...